1. Field of the Invention
The present invention generally relates to a method and apparatus for designing a high-frequency circuit, and a display method for use in designing a high-frequency circuit.
2. Description of the Related Art
Recently, it is common to use computer simulations to design electronic circuits and to evaluate circuit characteristics. However, this has a problem in that, when common component characteristic data items for use in designing high-frequency circuits, such as an image parameter (F parameter), an impedance parameter (Z parameter), an admittance parameter (y parameter), and a hybrid parameter (h parameter), are used, a designed high-frequency circuit cannot have the targeted circuit characteristics. Accordingly, recently, in order to eliminate the above problem, scattering parameters (S parameters) that represent the elements of a scattering matrix (S matrix) representing relationships between incident waves and reflected waves are used as component characteristic data items to design a high-frequency circuit and to evaluate circuit characteristics.
The S parameters have an advantage in that the use of the S parameters enables highly accurate evaluation of circuit characteristics because the S parameters are obtained by using a network analyzer to actually measure the frequency characteristics of component items. For circuit design and evaluation of circuit characteristics, S-parameter data tables for component items, provided by component manufacturers, must be prepared.
Since the S-parameter data tables provided by the component manufacturers basically bear magnitude and angles (phase) for measured frequencies, accurate evaluation of circuit characteristics cannot be performed for frequencies which are not described in the tables. Specifically, by using an S-parameter data table having magnitude and angles in units of 0.5 GHz, such as 0.5 GHz, 1.0 GHz, 1.5 GHz, 2.0 GHz, and 2.5 GHz, accurate evaluation of circuit characteristics cannot be performed for a frequency between two measured frequencies, such as 0.9 GHz, 1.2 GHz, and 2.3 GHz.